Purpose

This document describes how to set up and configure a single-node Hadoop
installation so that you can quickly perform simple operations using Hadoop
MapReduce and the Hadoop Distributed File System (HDFS).

Prerequisites

Supported Platforms

GNU/Linux is supported as a development and production platform.
Hadoop has been demonstrated on GNU/Linux clusters with 2000 nodes.

Win32 is supported as a development platform. Distributed
operation has not been well tested on Win32, so it is not
supported as a production platform.

Required Software

Required software for Linux and Windows include:

JavaTM 1.6.x, preferably from Sun, must be installed.

ssh must be installed and sshd must
be running to use the Hadoop scripts that manage remote Hadoop
daemons.

Additional requirements for Windows include:

Cygwin - Required for shell
support in addition to the required software above.

Installing Software

If your cluster doesn't have the requisite software you will need to
install it.

For example on Ubuntu Linux:

$ sudo apt-get install ssh$ sudo apt-get install rsync

On Windows, if you did not install the required software when you
installed cygwin, start the cygwin installer and select the packages:

openssh - the Net category

Download

To get a Hadoop distribution, download a recent
stable release from one of the Apache Download
Mirrors.

Prepare to Start the Hadoop Cluster

Unpack the downloaded Hadoop distribution. In the distribution, edit the
file conf/hadoop-env.sh to define at least
JAVA_HOME to be the root of your Java installation.

Try the following command:$ bin/hadoop
This will display the usage documentation for the hadoop
script.

Now you are ready to start your Hadoop cluster in one of the three supported
modes:

Local (Standalone) Mode

Pseudo-Distributed Mode

Fully-Distributed Mode

Standalone Operation

By default, Hadoop is configured to run in a non-distributed
mode, as a single Java process. This is useful for debugging.

The following example copies the unpacked conf directory to
use as input and then finds and displays every match of the given regular
expression. Output is written to the given output directory.
$ mkdir input$ cp conf/*.xml input
$ bin/hadoop jar hadoop-examples-*.jar grep input output 'dfs[a-z.]+'
$ cat output/*

Pseudo-Distributed Operation

Hadoop can also be run on a single-node in a pseudo-distributed mode
where each Hadoop daemon runs in a separate Java process.